Department of Animal Sciences, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA.
Biol Reprod. 2013 Feb 28;88(2):52. doi: 10.1095/biolreprod.112.104802. Print 2013 Feb.
Transient exposure to methoxychlor (MXC), an environmental endocrine-disrupting chemical, during fetal and neonatal stages causes ovarian dysfunction in pubertal, adult, and aging animals. Adult animals have reduced number of ovulations and abnormal follicular composition associated with altered gene expression and DNA methylation patterns. To test the hypothesis that the ovarian epigenomic changes induced by MXC are detectable following the exposure period, leading to altered gene expression by adulthood, we conducted a targeted genome-wide methylation study using Nimblegen 3x720K CpG Island Plus RefSeq Promoter Arrays. Control (vehicle), low-dose MXC (20 μg/kg/day), or high-dose MXC (100 mg/kg/day) treatments were administered between Embryonic Day 19 and Postnatal Day (PND) 7. Ovaries were collected at PND 7 immediately after exposure or at adulthood, PND 60. Array hybridizations were conducted with genomic DNA after methylated DNA immunoprecipitation and the array data were analyzed. DNA methylation events were functionally annotated, and candidate loci common to all the treatments or unique to some treatments were identified. Specific loci encoding signaling molecules such as the regulatory subunit p85 of phosphoinositide-3-kinase, insulin-like growth factor-1 receptor, Harvey rat sarcoma viral oncogene, insulin receptor, and forkhead box protein O3 were identified to be hypermethylated in MXC-treated ovaries at PND 7 and/or PND 60. Examination of gene expression changes with TaqMan low-density arrays revealed that nearly 25% of the genes that were assayed were downregulated. These data demonstrate that key molecules in specific signaling pathways such as PTEN signaling, IGF-1 signaling, or rapid estrogen signaling are epigenetically altered in MXC-exposed ovaries, which is associated with ovarian dysfunction and female infertility.
短暂暴露于环境内分泌干扰化学物质甲氧滴滴涕（MXC）会导致青春期、成年期和老年期动物的卵巢功能障碍。成年动物的排卵次数减少，卵泡组成异常，与基因表达和 DNA 甲基化模式改变有关。为了验证 MXC 引起的卵巢表观遗传变化在暴露期后是否可检测到，并导致成年后基因表达改变的假设，我们使用 Nimblegen 3x720K CpG 岛加 RefSeq 启动子阵列进行了靶向全基因组甲基化研究。对照组（载体）、低剂量 MXC（20μg/kg/天）或高剂量 MXC（100mg/kg/天）处理在胚胎第 19 天和出生后第 7 天（PND）之间进行。暴露后立即在 PND 7 或成年期（PND 60）采集卵巢。在甲基化 DNA 免疫沉淀后进行阵列杂交，并对阵列数据进行分析。对 DNA 甲基化事件进行功能注释，并鉴定所有处理或某些处理特有的共同候选位点。特定的基因座编码信号分子，如磷酸肌醇-3-激酶的调节亚基 p85、胰岛素样生长因子-1 受体、 Harvey 大鼠肉瘤病毒癌基因、胰岛素受体和叉头框蛋白 O3，在 PND 7 和/或 PND 60 的 MXC 处理卵巢中被鉴定为过度甲基化。使用 TaqMan 低密度阵列检查基因表达变化，发现近 25%的检测基因下调。这些数据表明，PTEN 信号、IGF-1 信号或快速雌激素信号等特定信号通路中的关键分子在 MXC 暴露的卵巢中发生了表观遗传改变，这与卵巢功能障碍和女性不孕有关。
